DIVIDENDS (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Dividends [Line Items]
Common dividends, (in dollars per share)	$ 0.44	$ 0.42	$ 0.42	$ 0.41	$ 0.40	$ 0.40	$ 0.38	$ 0.37	$ 1.69	$ 1.55	$ 1.37
Series D Preferred dividends (in dollars per share)										$ 0.74	$ 2.09
Ordinary income
Dividends [Line Items]
Common dividends, (in dollars per share)									$ 0.884	$ 0.989	$ 0.777
Series D Preferred dividends (in dollars per share)										$ 0.739	$ 2.094
Return of capital
Dividends [Line Items]
Common dividends, (in dollars per share)									$ 0.806	$ 0.561	$ 0.593
Series D Preferred dividends (in dollars per share)
Long-term capital gain
Dividends [Line Items]
Common dividends, (in dollars per share)
Series D Preferred dividends (in dollars per share)